1. Field of the Invention
The present invention relates to an image forming method and an image forming apparatus, and more particularly, to image recording technology which prevents curl, and the like, that occurs in a recording medium during image recording or after image recording.
2. Description of the Related Art
When printing using a water-based inkjet onto papers which are generally used in printing, such as art paper and coated paper, high-grade papers and other non-coated papers, there are known problems such as the occurrence of deformation of the paper, known as “curl”, due to the breaking and recoupling of hydrogen bonds between the cellulose fibers of the paper. As a countermeasure for preventing “curl”, there are methods such as adding a curl preventing agent, such as a sugar, to the ink, or using a strong paper suppressing mechanism in the conveyance unit and thus providing a mechanism which forcibly suppresses curl, but none of these methods suppress the curl to a sufficient degree.
Japanese Patent Application Publication No. 2004-136458 discloses a recording apparatus which deposits alcohol on paper prior to ink recording, so that the paper reaches a recording position in a state where the paper has substantially dried, and then records an image thereon. In the recording apparatus according to Japanese Patent Application Publication No. 2004-136458, due to the fact that the hydroxy groups in the alcohol solution bond with the hydroxy groups present at the bond points of the hydrogen bonds between the cellulose fibers, then even if water subsequently becomes present on the paper, the water molecules are repelled by the hydrophobic group part of the alcohol solution and are not able to reach the bonds between the fibers, and therefore in the process of drying the paper, movement of the bond points between the fibers is not liable to occur and curling of the paper is suppressed.
Japanese Patent Application Publication No. 9-254376 discloses an inkjet recording method and apparatus which deposits a treatment liquid that suppresses permeation of the ink, separately from the ink. Furthermore, U.S. Pat. No. 6,283,589 describes rendering a substrate hydrophobic before ejecting droplets of ink.
However, in the paper curl suppression method and the recording apparatus described in Japanese Patent Application Publication No. 2004-136458, it is known that since alcohol is deposited onto the paper before ejecting droplets of a water-based ink, then there are problems in that ink repellent and bleeding of the image may occur. In order to resolve these problems of repellent and bleeding of the ink, it could be considered to dry the surface of the paper after depositing the alcohol solution on the paper, but a problem has been discovered in that curl occurs again when ink droplets are subsequently ejected onto the paper. In other words, in technology disclosed in Japanese Patent Application Publication No. 2004-136458, the image properties and the suppression of curl are mutually conflicting factors and it is difficult to achieve both at the same time.
Furthermore, in the invention described in Japanese Patent Application Publication No. 9-254376, it is possible to cause the coloring material in the ink to insolubilize (aggregate) due to the action of the components (such as cationic surfactant, or the like) in the treatment liquid, and therefore permeation of the coloring material (dye) of the ink into the interior of the paper is suppressed reliably, but since the treatment liquid does not react with the solution (water component) of the ink, then it is not possible to suppress the solvent of the ink from permeating inside the paper. In other words, although Japanese Patent Application Publication No. 9-254376 claims to “suppress the permeation of ink”, in fact the invention described in Japanese Patent Application Publication No. 9-254376 simply suppresses the permeation of coloring material inside the ink and does not readily suppress curling of the paper.
In the invention described in U.S. Pat. No. 6,283,589, the capillary force received by the solvent in the ink is reduced by rendering the substrate (paper) hydrophobic in advance, and therefore the permeation of ink into the substrate is suppressed. On the other hand, in the invention described in U.S. Pat. No. 6,283,589, it has been discovered that since the spreading of the ink dots is also suppressed, then problems arise in that gaps occur between ink dots which are originally intended to overlap with (make contact with) each other, and as a result there is a problem in that the optical density declines markedly, and furthermore, “banding” caused by error in the dot positions becomes more pronounced.